Background: Endometrial Brush Cytology (EBC) has been proposed as a less invasive alternative to endometrial biopsy in women being evaluated for abnormal uterine bleeding, but the method has not gained popularity due to perceived challenges in interpretation and accuracy. Fluorescence in situ hybridization (FISH) has been tried as an adjunct test to improve diagnostic performance, but implementation is cost-prohibitive. The aim of this study was to evaluate various approaches to EBC diagnosis to improve accuracy.Design: Fifty EBC specimens had been collected immediately prior to hysterectomy and were processed using the ThinPrep method. These included 30 with benign and 20 with cancer (16 endometrioid, 4 non-endometrioid) histology. Seven blinded pathologists reviewed pre-screened slides after a 1 hour training session discussing diagnostic criteria with example cases. Pathologists classified the cases as non-diagnostic (ND), negative (N), atypical favor reactive (AFR), atypical favor neoplastic (AFN), or positive for malignancy (P). These screening levels were collapsed into negative (ND, N, AFR) and positive (AFN, P) for the purpose of statistical analysis. All cases were evaluated by FISH using probes directed to 1q25, 8p11, 8q24, and 20q13. Single locus gains and polysomy were considered positive, while normal results, tetrasomy, and ND were considered negative. Performance characteristics were calculated for FISH, the worst case scenario (WCS) single pathologist, random single pathologist, and consensus of 3 random panel pathologists (for each case), as well as combinations thereof.Results: Table 1.

Conclusions: Three pathologist consensus outperformed a random single pathologist. The addition of FISH improved the performance of the WCS pathologist, but did not improve the performance of a randomly selected pathologist from the panel. These results suggest that traditional single cytopathologist approaches might not be optimal for EBC interpretation, and that consensus approaches should be considered to improve accuracy. These findings are preliminary and need to be validated on a larger prospective cohort with population disease prevalence.Category: Cytopathology